AO Scope (Adjustable Objective) vs. SF Scope (Side Focus): What You Need to Know

AO scopes and SF scopes are two popular options for parallax correction in riflescopes. Both allow shooters to fine-tune focus for better accuracy, and understanding their differences helps you choose the right tool.

An AO scope adjusts parallax with a rotating ring near the front, offering precise focus control, especially beneficial for airguns shooters who need accurate parallax adjustments at close ranges. While the front-mounted adjustment may be less convenient for quick field changes, it's ideal for stationary shooting positions, making it a reliable choice for benchrest and precision work. AO scopes are also typically lightweight, which is advantageous for compact rifles or extended shooting sessions.

An SF scope, with its side-mounted dial, enables quick and convenient parallax correction without shifting position, making it popular among long-range shooters and hunters in fast-paced environments. While optimized for mid-to-long range, some models may offer limited focus at closer distances.

Specifically, for spring-piston rifles—especially break-barrel types—the scope is subjected to high recoil that can easily damage delicate optics. For these guns, a simple and robust scope design is essential, featuring:

• One-piece tube with thick walls and minimal seams – withstands heavy recoil and reduces the risk of damage.

• Etched glass reticle – improves durability under shock.

• Elevation and windage with locking turret or zero-stop – prevents accidental changes and maintains zero.

• Built-in AO adjustment – simple design with fewer moving parts for reliable focusing.

• Fixed or low-variable magnification – more stable under high recoil conditions.

VictOptics SOI 3-9×40 AO (VIOC-05) – Clear, accurate shots with close-range 5-yard AO adjustment, 5-level red/green illuminated reticle, and simple 1-inch tube design.

VictOptics SOI 4-12×40 AO (VIOC-06) – All VIOC-05 features plus higher magnification, 30mm tube and AO adjustment starting from 10 yards for longer-range versatility.

For more infomation about how to choose the right scope for airguns and air rifles, go check this helpful blog.

The Victoptics SOI series uses a 1-inch tube diameter, ensuring broad compatibility with standard mounting systems.

Explore more from Victoptics SOI series: SOI 1.5-5x20 (VIOC-01), SOI 2-7x32 (VIOC-02), SOI 3-9x40 (VIOC-03), SOI 4-12x40 (VIOC-04), SOI 3-9x40 AO (VIOC-05).